If it was faster then it wouldn't be the same as Burning Attack is now... and I thought the idea was just to fix the error (as BA is a ball in the show), rather than improve Burning Attack itself. Yes, if you made it into a faster ball, it would be effective. But that's not the same as just turning the BA attack into a ball and having no other changes.
If it simply changed into a ball, it would be a slowish ball that would be easier to dodge than an attached beam with some degree of mobility.
(edit: I should admit that I don't really know how fast the Burning Attack beam is, I just remember it moving slower than the Finishing Buster. If I'm wrong, let me know, and everything will be different.)